PET-CT Imaging in Lesions of the Tonsil for the Detection and Staging of Squamous Cell Carcinoma: A 3 Year Experience in 43 Cases.
Ramya P Masand, Guocheng He, Peeyush Bharagava, Linda K Green. Baylor C. of Med. and ME DeBakey VAMC, Houston, TX
Background: Positron Emission Tomography-Computerized Tomography (PET-CT) has a role in the staging of head and neck (H&N) squamous cell carcinoma (SCCs). In the pharyngeal palatine tonsil (PPT), it has been reported that there may be up to a 40% false positive rate. In the PPT, the calculated standardized relative uptake values (SUVs) on PET-CT is 3.48 +/- 1.3 in normal patients. It is reported that an SUV difference between right and left of 0.83 or > will pick up 100% of occult SCCs.
Design: We searched our files for tonsil biopsies performed since 2005. We reviewed the clinical, radiographic, pathologic findings. PET-CT was performed in selected patients using 18F-FDG PET fused with a low dose non-contrast CT scans. The tonsil location SUVs were recorded and compared to pathologic data. Other sites of increased SUV uptake were also recorded.
Results: There were 901 patients with tonsil histology. There were 43 patients with PET-CT scans. The SUV values in the PTTs ranged from 0 to 35. There were 19 biopsy negative cases which showed either reactive hyperplasia or atrophy (Table 1). All cases with SCC in the H&N region were diagnosed prior to the PET-CT scan via tonsil biopsy or biopsy of a another site (lymph node or another H&N location). No occult SCCs were found with PET-CT. There were 2 cases (SUV 0) in which the biopsy showed SCC. SUV values between the right and left tonsils did not predict cancer. The patients with SCC SUVs ranged from 0-35 and patients without SCC ranged from 2.8-8.2 (Table 1). Over 33% of patients with a high SUV on PET-CT had no SCC at tonsil biopsy. In tonsil SCC, there was a false negative rate of 35%.
|SUV number||Tonsil with SCC||Tonsil Negative|